Electrothermal device for coagulating, sealing and cutting tissue during surgery

ABSTRACT

An instrument and method are provided for sealing and joining or hemostatically dividing tissue, which is particularly suitable for laparoscopic and endoscopic surgery. The instrument makes use of the controlled application of a combination of heat and pressure to seal adjacent tissues, to join adjacent tissues, or to anastomose tissues, whereby tissue is heated for an optimal time and at an optimal temperature under optimal pressure to maximize tissue seal strength while minimizing collateral tissue damage. The instrument of the present invention is lightweight and therefore portable, and is particularly useful in field conditions where a source of external power may not be readily available. 212/324

[0001] This application is a divisional of co-pending U.S. patentapplication Ser. No. 09/374,563, filed Aug. 13, 1999 which is acontinuation- in-part of co-pending U.S. patent application Ser. No.09/035,691, filed Mar. 5, 1998, which is based upon U.S. provisionalpatent application Serial No. 60/038,589, filed Mar. 5, 1997, both ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to instruments andmethods for sealing and joining or cutting tissue. The instruments ofthe present invention are especially intended for use during eitherconventional open surgery or endoscopic or laparoscopic surgery.

BACKGROUND OF THE INVENTION

[0003] Hemostasis, or blood clotting, can be obtained by the activationof a naturally occurring biological pathway known as the coagulationcascade. The pathway can be activated by tissue injury. This injury cancome from mechanical, chemical or thermal sources. This naturalbiological pathway results in the conversion of freely flowing blood toa blood clot. Several biological elements are involved in thecoagulation cascade, including tissue proteins, mainly fibrin andthrombin. Cells such as platelets and red and white blood cells are alsoinvolved.

[0004] During surgery, hemostasis can also be achieved by directdenaturization of the proteins found in the blood. Denaturization of aprotein means that its characteristic three dimensional structure isaltered without actually breaking up the protein. This directdenaturization is a purely physico-chemical process in which thedenatured proteins bond together, forming an amorphous mass of proteinwhich is comparable to a naturally occurring clot. How does denaturing aprotein cause it to stick together with neighboring proteins? Proteinsgenerally have a complex three-dimensional structure. A protein isactually a chain of smaller molecules called peptides, which peptidesmay have side-chains which contain a molecular group which can attract amolecular group on another side chain. The main protein chain is loopedand folded on itself in a complex way which results in thethree-dimensional structure characteristic of the protein. This loopingand folding occurs because of an intra-molecular attraction betweenside-chains of the peptides. This attraction between side-chains isgenerally of the “hydrogen bond” or electrostatic type. The attractionwhich holds the peptides together along the main chain is a covalentbond. When a protein is denatured, it loses its normal three-dimensionalstructure. As a result of this unfolding of the protein molecule, theside-chains on the peptides, instead of facing “inward” to fold up theprotein chain are now able to bond to side chains from proteins whichare neighbors. This inter-molecular bonding results in the formation ofa lump of denatured protein. This process is not dependent on theactivation of the biological cascades of the natural clotting mechanism,but it is a purely physicochemical process. For hemostasis, the tissueproteins which must be denatured are chiefly those in blood such ashemoglobin and albumin but also include structural proteins such asthose found in the wall of blood vessels or in other anatomicalstructures.

[0005] One of the best ways to denature a protein is to heat it up to atemperature high enough to cause the intra-molecular hydrogen bonds tobreak, but which is not high enough to break the much strongerpeptide-peptide covalent bonds along the main chain. A prime example ofthis process is the heating up of the clear part of an egg until itturns white. This white color means that the original clear protein hasbeen denatured.

[0006] Heat which is delivered to tissue proteins may start out aselectrical energy, light energy, radio wave energy, or mechanical(vibrational or frictional) energy. As far as the tissue is concerned,it does not matter what the original source of the original energy is,as long as it gets converted in some fashion to heat.

[0007] For example, if the source of the energy is a laser, then thelight energy is absorbed by molecules in the tissue whose absorptionspectrum matches the wavelength of the laser light being used. Once thelight energy is absorbed, heat is produced, and the physico-chemicalprocess of protein penetration is achieved. Any sort of light energywill have this effect, if its wavelength is such that it can be absorbedby the tissue. This general process is called photocoagulation. Theadvantage of using a laser is that since its output is monochromatic,one can selectively heat certain tissue elements which have the rightabsorption spectrum, while sparing other tissue elements for which thelaser light is not absorbed. This principle is used commonly inophthalmology. Another advantage of using a laser is that its coherentand collimated beam can be very tightly focused on very small targets.If one does not care about spatial precision or selectivephotocoagulation of only certain tissue elements, then it is perfectlypossible to coagulate tissue by using a very bright but otherwiseordinary light.

[0008] If the source of energy is electrical currents flowing throughthe tissue, the process is called “electrosurgery”. What happens here isthat the current flowing through the tissue heats up the tissue becausethe tissue has resistance to the flow of electricity (“Ohmic heating”).In the case of ultrasonic coagulation, the rapid vibration of theultrasonic element induces heating in essentially the same fashion asthe production of fire by rubbing sticks together (although the rate ofvibration is much much higher and the process is more controllable).

[0009] Since it is heat that denatures and coagulates proteins, why goto all the trouble of starting with a laser or an electrosurgery unit?Why not just use a very simple source of heat, such as a resistance wireor, even simpler, a hot piece of metal? In antiquity, “cautery” via ahot piece of iron was used to staunch bleeding wounds. The problem withthis approach is not efficacy, it is control and containment of theamount and extent of tissue which is cauterized or injured.

[0010] In fact, the development of “electrocautery” in the late 1920'sby Professor of Physics William T. Bovie was spurred by the desire (ofthe pioneering neurosurgeon Dr. Harvey Cushing) to have a morecontrollable and refined means of producing heat in tissues thanpossible by using a large piece of heated metal. Electrocautery usesvery high frequency alternating electrical current, since it was foundthat these high frequencies did not cause tetanic (“Galvanic”)stimulation of muscle tissue which occurs when direct current or lowfrequency current is used. To avoid muscular stimulation, it isnecessary to use alternating currents with very high frequencies, aboutseveral hundred thousand cycles-per-second. This high frequency falls inthe range of the AM radio band, which is the reason why many electricalinstruments such as monitors used in the OR will register interferencewhen electrocautery is activated. There are many potential problemsstemming from the use of such high frequencies, including difficulty incontrolling stray currents which can injure patients and interfere withpacemakers and computer equipment. Electrocautery has been refined overthe past fifty years, but it still represents a rather round-about wayof getting tissue to heat up.

[0011] Numerous instruments are known which coagulate, seal, join, orcut tissue. For example, there are electro-surgical instruments, bothmonopolar and bipolar, which use high frequency electrical current thatpasses through the tissue to be coagulated. The current passing throughthe tissue causes the tissue to be heated, resulting in coagulation oftissue proteins. In the monopolar variety of these instruments, thecurrent leaves the electrode and after passing through the tissue,returns to the generator by means of a “ground plate” which is attachedor connected to a distant part of the patient's body. In a bipolarversion of such an electro-surgical instrument, the electric currentpasses between two electrodes with the tissue being placed or heldbetween the two electrodes as in the “Kleppinger bipolar forceps” usedfor occlusion of Fallopian tubes.

[0012] There are many examples of such monopolar and bipolar instrumentscommercially available today from companies including Valley Lab, Cabot,Meditron, Wolf, Storz and others worldwide. A new development in thisarea is the “Tripolar” instrument marketed by Cabot and Circon-ACM1which incorporates a mechanical cutting element in addition to monopolarcoagulating electrodes.

[0013] With regard to known ultrasonic instruments, a very highfrequency (ultrasonic) vibrating element or rod is held in contact withthe tissue. The rapid vibrations cause the proteins in the tissue tobecome coagulated. The ultrasonic instrument also employs a means forgrasping the tissue while the proteins are being coagulated.

[0014] Olympus markets a heater probe instrument which uses anelectrical heating wire contained in a catheter type flexible probemeant to be passed through a flexible endoscope. It is used to coagulatesmall bleeding vessels found on the inside of the gastrointestinal tractor the bleeding vessels found in peptic or other sorts ofgastrointestinal ulcerations. In this instrument, no electrical currentpasses through the tissues, as is the case for monopolar or bipolarcautery. This instrument would certainly not be suitable for use inlaparoscopic or open surgery in which large amounts tissue must be notonly coagulated but also divided.

[0015] There are a number of relevant patents:

[0016] Pignolet, U.S. Pat. No. 702,472, discloses a tissue clampingforceps with jaws wherein one has a resistance for heating the jaw, anda battery to power the heater. The coagulated tissue caused by the heatand pressure is subsequently severed along the edges of the jaws beforethey are opened;

[0017] Downes, U.S. Pat. No. 728,883, teaches an electrothermicinstrument having opposing jaw members and handle means for actuatingthe jaws. A resistance member is installed in the jaw member, which isclosed to direct contact by a plate. This instrument coagulates tissueby heat, not electrical current, applied to the tissue;

[0018] Naylor, U.S. Pat. No. 3,613,682, discloses a disposablebattery-powered cautery instrument;

[0019] Hiltebrandt et al., U.S. Pat. No. 4,031,898, concerns acoagulator with jaw members, one of which contains a resistance coil.This instrument has a timer mechanism for controlling the heatingelement. The heating element is used directly as a temperature sensor;

[0020] Harris, U.S. Pat. No. 4,196,734, teaches a instrument that caneffect both electrosurgery and cautery. A thermistor temperature—sensingelement monitors a heating loop and regulates the current and therebythe temperature;

[0021] Staub, U.S. Pat. No. 4,359,052, relates to a cautery instrumentwith removable, battery-powered cautery heating tip;

[0022] Huffman, U.S. Pat. No. 5,276,306, discloses a pistol grip,hand-held heating instrument having a trigger mechanism for the battery;

[0023] Anderson, U.S. Pat. No. 5,336,221, teaches an optical thermalclamping instrument for welding or fusing tissue, and employing acutting blade for separating the fused tissue;

[0024] Stern et al., U.S. Pat. No. 5,443,463, discloses clamping jawmembers that are bifurcated by a cutting blade, having plural electrodesand temperature sensors, and can function as monopolar or bipolar; and

[0025] Rydell, et al., U.S. Pat. No. 5,445,638, relates to a bipolarcoagulation and cutting instrument.

[0026] While each of the above-mentioned references is relevant to theinvention herein, none teaches or suggests the totality of the inventiontaught and claimed here.

OBJECTS OF THE INVENTION

[0027] It is an object of the present invention to provide a instrumentfor sealing, cutting, or sealing and cutting tissue.

[0028] It is also an object of the present invention to provide ainstrument for sealing and joining tissue.

[0029] It is another object of the present invention to provide aportable instrument which does not require an external power source.

[0030] It is a further object of the present invention to provide ainstrument which can be constructed to conform to the requirements oflaparoscopic and endoscopic surgery, i.e., to be long and very narrow,in the range of a few millimeters in diameter or even narrower.

[0031] It is still another object of the present invention to providefor a method for carrying out surgical procedures using the instrumentof the present invention.

[0032] It is a still further object of the invention to provide a methodand apparatus for optimal heating and optimal pressure to optimizetissue seal strength and to minimize collateral damage to tissue.

[0033] These and other objects of the invention will become apparent toone skilled in the art from the following more detailed disclosure ofthe invention.

SUMMARY OF THE INVENTION

[0034] According to the invention, there are three parameters that areindependently controlled—the temperature to which tissue is heated, thepressure which is applied, and the time over which the temperature andpressure are maintained. The total heat applied to the tissue is afunction of the temperature and the time. A key feature is the combined(simultaneous, partially simultaneous, or sequential) application ofpressure and heat to the tissue being coagulated for a specified amountof time, which induces the denatured proteins to bond together, which inturn assists in attaining hemostasis with less heat energy than would berequired without the pressure Also, the total energy applied isminimized by means of the configuration and materials of the parts ofthe instrument that hold the tissue in opposition during the applicationof the heat and pressure. Using less heat energy means less collateraldamage. In addition, results can be achieved that are at least as goodas can be achieved with known electro-surgical and ultrasonic tissuecoagulation units, but with a much smaller, lighter power source, suchas a battery. Also, a very simple and direct method of heating thetissue is used. Since the basic heating element is so simple, theimproved results can be achieved at a fraction of the cost of the moreround-about means of heating tissue.

[0035] According to one aspect of the present invention instruments andmethods for sealing, or coagulating, and cutting tissue during surgeryare provided. The instruments incorporate means for controllably heatingtissue while simultaneously applying a definite and controllable amountof pressure to the tissue being heated. Because of the combinedapplication of heat and pressure, tissue proteins will become coagulatedand blood vessels within the tissue will be sealed shut, achievinghemostasis. Optimal sealing or coagulating tissue means producing astrong and durable seal or coagulation or anastomosis with a minimalamount of collateral tissue damage. In the instruments of the inventionoptimization is achieved by a combination of the physical configurationof the part of the instrument that holds the tissue during thecoagulation process and regulation of the time, temperature, andpressure.

[0036] As part of the temperature control, heat can be applied in pulsesrather than in a continuous manner. Pulsed heat application allowstissue that is adjacent to the area being coagulated time to recoverfrom the heating process and to remain viable. Also, the application ofthe pressure may be variable in intensity and may also be applied in apulsed or discontinuous manner.

[0037] It is an aspect of the present invention to provide a method andinstrument for the surgical treatment of biological tissue, whereinthermal energy and pressure are applied simultaneously, substantiallysimultaneously, consecutively, or alternatively, over a time such thattissue proteins are denatured and the tissue will adhere or join toitself or to other tissues, for the purpose coagulating bleeding,sealing tissue, joining tissue and cutting tissue. The minimum amount ofheat or thermal energy needed to accomplish these goals is expended, soas to minimize thermal damage to tissue adjacent to the treated site.

[0038] The instruments of the invention may also incorporate means forcutting, or severing, the tissue after the tissue has been coagulated,“cutting” including dissecting or tissue division, tissue disruption orseparation, plane development, or definition or mobilization of tissuestructures in combination with a coagulation or hemostasis or sealing ofblood vessels or other tissue structures such as lymphatics or tissuejoining. The cutting can be achieved by means of a blade which is passedthrough the coagulated tissue while the tissue is being held in the jawsof the instrument. Cutting can also be achieved thermally by use ofamounts of heat greater than the amount required to coagulate thetissues. Alternatively, cutting can be achieved by other mechanical,ultrasonic, or electronic means, including, but not limited to, shearingaction, laser energy, and RF, or a combination of two or more of theabove. In the case of using thermal energy to achieve tissue cutting,the instruments and methods minimize the amount of energy required todivide tissues with the least amount of unwanted tissue necrosis.

[0039] The heating element may be a resistance wire through whichelectric current is passed, or the heating element may be anothermaterial which generates heat when electrical current is passed throughit. The electrical current is applied through the wire either as acontinuous current or as a series of pulses of definite duration andfrequency. Unlike conventional electro-surgical instruments, theelectric current of the instruments of the invention does not passthrough the tissue, which can cause problems due to stray electriccurrents. The electrical elements are electrically insulated from thetissue while being in good thermal contact. In a simple embodiment ofthe instrument, the total amount of continuous current and hence thetotal heat energy applied to the tissue, is limited in duration by asimple timer circuit or even by direct visual or other sensoryinspection of the treated tissue. In a more sophisticated embodiment,the pulse train configuration and duration is under control of a simplemicrocontroller, such as, for example, an embedded microprocessor. Withmicroprocessor control, a thermistor heat sensor is incorporated intothe part of the instrument that grasps the tissue being coagulated. Themicroprocessor takes temperature readings from the thermistor andadjusts the pulse train configuration and duration to achieve theoptimum temperature to cauterize or seal the tissue while minimizingunwanted collateral thermal damage. The actual value of the optimumtemperature can be verified experimentally for this particularinstrument.

[0040] The temperature of the sealing treatment according to one aspectof the invention is preferably kept in the range required to denaturatetissue proteins (approximately 45 C. to below 100 C. while avoidingexcessive necrosis to the tissue. Keeping the temperature in the rangerequired to achieve protein denaturization without excessive tissuenecrosis means that the total heat energy expended in the treatment willbe less than if the temperature were not kept in this range. The amountof heat energy expended in the treatment is related to the degree of theheat (the temperature) and the length of time for which the heat isapplied. The combined application of pressure with the heat reduces theamount of heat or the degree of temperature that would be required tohave the denatured proteins actually stick together. This combinedapplication of pressure also increases the strength with which thedenatured proteins actually stick together, for a given amount of heatenergy at a given temperature.

[0041] The amount of pressure applied is regulated by springs or otherelastic elements, or mechanically functional equivalents, which willresult in the tissue being held with a predetermined amount of force perunit area, in spite of variations in the size or thickness of the tissuebeing sealed or coagulated. The pressure may also be regulated bymechanical elements or spacers or by the geometry of the pressureproducing elements. As with the temperature value, the exact value forthe pressure to be applied can be verified for this instrument withappropriate measurement calibration.

[0042] The controlled application of a combination of heat and pressurewhich is sufficient but not excessive to produce a durable coagulationor seal has the result that only a relatively small amount of heatenergy is needed. That only a relatively small amount of heat is neededmeans that relatively small electrical batteries can be used as theenergy source to produce the heat. A instrument of the invention cantherefore be free of bulky and heavy external power generators such asare required with conventional electro-surgical, laser or otherinstruments for coagulating tissue. Because small batteries can be usedto power the instrument, the instrument can be made quite compact andlight weight, as well as portable and/or disposable. The use ofbatteries or other sources of low voltage direct current facilitates theavoidance of hazards and inconveniences caused by electricalinterference and stray currents, which occur in conventionalhigh-frequency electro-surgical instruments. Laser eye hazards are alsothereby avoided.

[0043] Since the heating elements and pressure producing elements of theinstrument may be inherently simple and inexpensive to manufacture, thepart of the instrument that comes in contact with tissue can be made ina disposable manner, if desired, while the more expensive portions ofthe instrument can be made to be reusable. If the instrumentincorporates a simple timer, instead of the microprocessor-thermistorcontroller, the entire instrument including batteries can be made veryinexpensively and to be disposable.

[0044] Different embodiments of this instrument employing the samegeneral principle of controlled application of a combination of heat andpressure can be used to join or “weld” adjacent tissues to produce ajunction of tissues or an anastomosis of tubular tissues. The joining oftissues is essentially a special case of the controlled coagulation oftissue proteins to achieve hemostasis.

[0045] It is a further aspect of the present invention that such heatand pressure effects will be spatially confined by the physicalconfiguration and materials employed in the construction of theinstrument. The configurations and construction materials are such that(1) the tissue is held in apposition with enough pressure to effect astrong union of the denatured proteins but not enough pressure to causenecrosis of the tissue, and (2) the heat is concentrated on the tissuebeing treated by means of the material of the jaws which hold the tissuebeing treated, such material being a thermal insulator which preventsthe heat from being expended on heating adjacent tissues. Such materialmay also employ a reflective layer or coating to reflect back thetreated tissue heat energy that would otherwise be lost to thermalradiation. Such material may also have a geometry or be shaped in such away to focus the thermal energy on the treated tissue and away fromtissue not intended to be treated. For example, the jaws of theinstrument may have a concave or parabolic inner surface to focus thethermal energy.

[0046] It is a further aspect of the present invention that such effectswill be spatially confined by the kind, amount, and duration andtemporal distribution of the energy delivery. The energy could originateas heat, light, sound or electricity, chemical, or other forms ofenergy, as long as this energy is converted to heat to denature tissueproteins. In a preferred embodiment, the energy would be delivered froma simple, low cost thermal heating element which could be powered by abattery contained in the instrument itself. The energy could bedelivered in a continuous, or pulsed or intermittent mode, at variableor constant intensity. Pulsed or intermittent delivery of energy canproduce a spatial confinement of the energy distribution. Feedback(including optical, thermal, spectroscopic, among others) and amicroprocessor could be used to control the thermal effect. In the caseof tissue coagulating, sealing or joining, the temperatures produced bythe energy source could be the range of from about 45 C. to about 100 C.for a duration long enough to produce denaturation of the proteins inthe treated tissue.

[0047] The heat or energy delivery source may be a simple electricallyresistant wire, straight or curved, a grid or pattern of wires, or athin-film or coating of electrically resistant material. One or moreenergy elements may be used. They may target some or all of the tissuetreated by the pressure elements. The energy delivery source may beintegral with or separate from the pressure elements. Cutting elementsmay be incorporated into the energy elements. The energy or heat sourcemay move or be fixed. The energy may be delivered in a similar ordissimilar plane compared to the direction of pressure application. Theenergy or heat source may be constructed in such a way that its shapeand size may be varied to conform to different anatomical situations,tissue shapes and thicknesses. For example, an inflatable balloon coatedwith an electrically resistant material might be employed as the heatsource. Another example would be that the heat source might have anexpandable f an type configuration which could enlarge (“fan out”) tocover a larger surface or a smaller surface as needed. Another examplewould be a flexible sheet type configuration that could wrap around thetissue to be treated.

[0048] It is a further aspect of the present invention that such effectswill be spatially confined by the kind, amount, and duration or temporaldistribution of the pressure delivery acting in conjunction with theenergy or heat source. The delivery of pressure will usually be from aminimum of two elements of the apparatus rather but may in some cases befrom simple abutment or pressing of a single element against tissue, asin the example of the circular cutting wheel or a coring biopsyinstrument. Any combination of geometric arrangement between the energysource and the pressure source may be produced, including combinedenergy pressure sources and separate energy and pressure sources. Aconstant requirement is that the energy element deliver energy to atleast some of the tissue that is subjected to pressure by the pressureelement. The pressure element likewise may be variable in its shape,being able to adjust its shape before or during the application of theenergy or pressure to accommodate for different anatomical situations,tissue shapes or thicknesses. Cutting elements or other elements forshaping or forming the tissue may be incorporated with the pressureelement. For example, the pressure element may be comprised of aflattened side with an acute up-angled center to produce a combinationof cutting effect over the center with compression along the sides. Thepressure applied may be constant or variable over time and the relationof the pressure elements to the tissue may be constant or variableduring application of the pressure and energy or both. Motion of theappropriately configured pressure elements may be used to effect cuttingbefore, during or after application of the energy or pressure. Thevariable application may likewise be controlled by feedback frompressure transducers or strain sensors acting with a microprocessor.

[0049] It is a further aspect of the invention that a completelyseparate cutting element could be used in addition to separate energyand pressure elements. It is also an aspect of the invention thatmechanical tissue fastening instruments including sutures, staples,clips, bands, screws, plates or tacks could be incorporated into theinstrument. In this case the thermal energy and pressure would be usedto provide mainly coagulation and sealing and the mechanical elementswould provide additional strength to the tissue joint or anastomosis.

[0050] The invention can be used in either open, laparoscopic,endoscopic or any form of minimally invasive surgery. Surgicalinstruments based on this invention could be long and thin, suitable forlaparoscopic or minimally invasive approaches.

[0051] The parameters of temperature, time, pressure, as well as the anyadjustable physical configuration or geometry of the instrument mightvary depending on the type, size, and thickness of tissue being treated.These parameters may be experimentally determined before the actualtreatment and incorporated into the instrument by means of a “look-up”table in a microprocessor or by means of simple markings andcalibrations of adjustable knobs, dials, etc., of the instrument.

[0052] For the purpose of thermally joining or anastomosing two hollowtubular structures, e.g., small blood vessels or vas deferens, apreferred embodiment would incorporate two circular or cylindricalelements. Such cylindrical elements would be designed to fit one intothe other, acting as a jug or temporary stent which would hold the twotubular structures together while heat was applied. The tubularstructures would be held in such a way to provide either a certainamount of overlap or end-to-end contact. As in previous embodiments, theamount of coaptive pressure which is being applied would be optimizedaccording to the tissue type and thickness. The heat would be providedby a heating element or elements incorporated into the cylindrical jigsor stents and situated to apply the heat to the parts of the two tubularstructures which are in overlap or in end-to-end contact. As discussedabove, the amounts of heat and pressure applied are the minimum requiredto produce a secure anastomosis with the least amount of collateraldamage.

[0053] Another embodiment of this instrument would employ a circularmechanical cutting element, suitable for obtaining “core” biopsies ofsolid organs such as the liver or a kidney. This circular mechanicalcutting element, shaped like a cylinder with sharp edges at one end,would incorporate an electrically resistant element on the outside ofthe cylinder. This electrically resistant element could be in the formof a thin film of resistance material. As the mechanical cutting of thetissue was done by rotating or pushing the cylindrical cutter into thetissue, hemostasis along the track created by the cutter would beachieved by the heating element on the outside of the cutter. Thecylindrical cutter would be constructed out a material, or wouldincorporate a layer of a material, such that the tissue core samplebeing removed would be insulated from the thermal effects of the heatingelement on the outside of the core. This design would allow forretrieval of tissue samples which are not distorted by heat changes andalso allow for secure hemostasis along the tract of the biopsy. In thisinstrument, the lateral pressure exerted by the cylinder wall on thetissues of the track cannot be explicitly controlled; however, there ispressure, and this pressure is part of attaining hemostasis.

[0054] In a further embodiment of the invention, a circular cuttingwheel would be mechanically rotated to cut tissue, such as skin. Thiscircular cutting wheel would incorporate along its rim, an electricallyresistant thin film. This electrically resistant element would providefor hemostasis as the rotating mechanical wheel cuts the tissue.

[0055] In a yet further embodiment of the invention, an inflatableelastic balloon could be used to apply heat and pressure to tissue. Theexterior surface of the balloon would be coated partly or totally withflexible, optionally stretchable, electrically resistant material thatwill heat up when electrical current is applied. Here, the pressureexerted on the tissue can be controlled by regulation of the inflationpressure of the balloon.

[0056] Another embodiment of the invention comprises a compactelectrical cutting and coagulating instrument which allows bloodvessels, other vessels in the body, or organ tissue to be divided withelectrical energy while at the same time being ligated by heat-inducedcoagulation. This embodiment comprises a forceps or tweezer-like gripperwith two arms which may grasp a vessel or section of organ tissue withgripping areas at the tip of the arms. One arm is fitted with aprotruding cutting wire, while the other arm is provided with an anvilsurface and, optionally, a recess for receiving the cutting wire.Cutting a vessel or tissue is accomplished by heating the wire andclosing the tweezer arms on the vessel or tissue, allowing the hot wireto cut the vessel or tissue. Sealing the vessel or tissue isaccomplished when the tweezer arms have closed upon the severed ends ofthe vessel, whereupon the anvil surface is heated to cause coagulationof the vessel or tissue. The wire may be made of a non-stick compositioncomprising carbon, and the anvil may comprise non-stick substances suchas PTFE or carbon. The cutting wire is heated to a high temperature froman electrical power source, preferably a DC power source, and preferablypowered by batteries housed in the body of the instrument or in aportable battery pack. The anvil may be heated by radiant and conductiveheat from the cutting wire, with heating wires powered from theelectrical power source, or from the cutting wire indirectly.

[0057] Optionally a standard clamp can be modified to accept a cartridgecontaining a heating element and a power supply, or an instrument usefulfor laparoscopic procedures may be the functional equivalent of theforceps described above.

[0058] The instruments of the invention can be used in surgery and areparticularly well suited to laparoscopic and endoscopic surgery. Becausethe method described uses heat energy in the minimum amount and at thelowest temperature consistent with attaining denaturation and stickingtogether of tissue proteins, instruments which work based on this methodwill be able to function more efficiently than conventional surgicalenergy instruments. Therefore these instruments can be portable and evenbattery powered, which makes them ideally suited for portable ormilitary applications.

[0059] There is no instrument or method in the prior art whichspecifically seeks to obtain surgical coagulation, sealing, joining orcutting by a combination of resistant heat energy and pressure at atime, temperature and pressure which together are sufficient but notexcessive to produce protein denaturization, and with a physicalconfiguration and materials of construction which promote the stickingtogether of the tissues being treated while min losses of heat energy tosurrounding tissues beyond the treatment zone.

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Reference is made to the following description taken inconnection with the accompanying drawings, in which:

[0061]FIG. 1 is a schematic representation of one embodiment of thepresent invention;

[0062]FIG. 1A is a cross-section along line I-I of the embodiment inFIG. 1 with the Jaw in closed position;

[0063]FIG. 2 is a top, partly cross-sectional view of the lower jaw ofthe embodiment of FIG. 1 showing the heating and cutting elements;

[0064]FIG. 3 is a plan view of another embodiment of the invention;

[0065]FIGS. 4 and 5 are cross-sectional views of the embodiment of FIG.3;

[0066]FIGS. 6 and 6A are a plan view and a partial, enlarged view,respectively, of a further embodiment of the invention;

[0067]FIGS. 7 and 7A are a plan view and a partial cross sectional view,respectively, of another embodiment of the invention;

[0068]FIG. 8 is a partly cross-sectional view of a further embodiment ofthe invention;

[0069]FIG. 9 is a plan view of yet another embodiment of the invention;

[0070]FIG. 10 is a top, partly cross-sectional view of the embodiment ofFIG. 9;

[0071]FIG. 11 is a plan view of another embodiment of the invention forheating and cauterizing tissue;

[0072]FIG. 12 is a prospective view of a forceps embodying a cuttingand/or coagulating element in accordance with the invention;

[0073]FIG. 13 is a top view of the embodiment shown in FIG. 12;

[0074]FIGS. 14 and 15 are each partial views of a forceps arm from theembodiment shown in FIG. 12;

[0075]FIG. 16 is a cross-sectional view of the distal portions of theforceps arms shown in FIG. 12;

[0076]FIG. 17 is a graphic representation of the temperature gradient oftissue heated with the embodiment of FIG. 12;

[0077]FIG. 18 is a graphic representation of the time vs. temperaturecharacteristics of the embodiment of FIG. 12;

[0078]FIGS. 19 and 20 are prospective views of a clamp embodiment of theinvention;

[0079]FIG. 21 is a perspective view of an embodiment of the inventionspecifically adopted for laparoscopic use.

[0080]FIG. 22 is a partially cross-sectional view of the distal end ofthe embodiment shown in FIG. 21;

[0081]FIG. 23 is a partially cross-sectional schematic detail of anembodiment of the distal end shown in FIG. 22; and

[0082]FIGS. 24 and 25 are each a schematic, partially cross sectionalview of another embodiment of the invention adapted for laparoscopicuse.

DETAILED DESCRIPTION OF THE INVENTION

[0083] The invention can perhaps be better appreciated from thedrawings. FIG. 1 depicts a schematic representation of the instrument ofthe invention showing an upper jaw 10, a lower jaw 12, an elongatedshaft 14 attached to a handle 18, having a lever 20 for opening andclosing the jaws. Upper jaw 10 is attached at hinge 11 to spring supportmember 13, and spring 15 is attached to both upper jaw 10 and springsupport member 13 to bias upper jaw 10. Lever 20 is operativelyconnected through rod 21 to one or both of upper jaw 10 and lower jaw12. The end of shaft 14 closest to handle 18 is provided with (1) apusher 16 which is operatively connected through member 17 and connector23 to a cutting knife blade 19 housed in lower jaw 12 and (2) a trigger22 to actuate pusher 16 which in turn actuates cutting blade 19. Thelower end of handle 18 is provided with a rechargeable battery pack 24,which is operatively connected to heating element actuator 27 andheating wire element 26 in lower jaw 12.

[0084] In FIG. 1A, tissue segment 25 is clamped between jaws 10, 12,where it can be cut by blade 19.

[0085]FIG. 2 depicts a top view of lower jaw 12 showing the relativelocations of heating wire element 26 and a slot 28 for cutting blade 19,within jaw 12. Heating wire element 26 is in a groove of a depth suchthat the wire is substantially flush with the surface of jaw 12.Preferably the distal portion 29 of heating wire element 26 is below, orout of, the plane of heating wire element 26 so that only two parallelareas of tissue will be sealed. Heating wire element 26, whichpreferably is comprised of nichrome or another suitable electricallyresistant metal or alloy, or an electrically resistant thin-film orcoating will preferably have a suitable, thermally conductive,electrically resistant, non-stick coating. Examples would includepolytetrofluoroethylene (PTFE), e.g., TEFLON®, or other nonstickcoatings used in cookware. Moreover, one or both of the facing surfacesof upper jaw 10 and lower jaw 12 may optionally be corrugated,irregular, or grooved.

[0086] Both the upper and lower jaws are composed of a material, such asceramic, which is thermally insulating or thermally reflective. In thisway, the heat generated by the heating element is confined to the spacebetween the jaws, and is not allowed to spread or radiate to othertissues that may be in contact with the outside of the jaws. This isbeneficial in two ways: first, the heat generated by the heating elementis used efficiently to perform the desired sealing or coagulation, andsecond, surrounding tissues are protected from inadvertent thermalinjury.

[0087] s would be appreciated by one skilled in the art, the heating,pressure, and/or cutting functions could be mechanically,electromechanically, or electronically synchronized to obtain optimalresults according to the invention. Also, the instrument shown in FIGS.1, 1A, and 2 may optionally not have a cutter element. Such a instrumentwould be intended for situations where only heating and pressure wouldbe necessary to join tissue or to otherwise heat and cauterize tissue toproduce coagulation.

[0088] In the embodiment of the invention shown in FIGS. 3 and 4, acylindrical member 30 is concentrically positioned around a rod 32, thedistal portion of which forms anvil 33. The distal surface ofcylindrical member 30 comprises a circular heating element 34 and acircular cutting element 35 arranged concentrically within heatingelement 34. Anvil 33 is configured so that when rod 32 is movedproximally, the proximal circular edge 36 of anvil 33 cooperates withheating element 34 to coagulate or seal tissue.

[0089] Use of the embodiment of FIGS. 3 and 4 can be appreciated in FIG.5, where, for example, two sections of intestine 38,39 are positioned tobe joined together. Initially one end of each of sections 38,39 isloosely connected with ligatures 40,41 about rod 32. Then, rod 32 ismoved distally to cause circular edge 36 of anvil 33 to force portionsof intestines 38,39 into contact with heating element 34. Intestinesections 38,39 are joined together, and excess tissue is cut off bycutting element 35. Rod 32 is then pulled further in the proximaldirection to remove the excess tissue, cylindrical member 30, and anvil33.

[0090] In addition, the instrument shown in FIGS. 3 to 5 to producecircular anastomosis by relying on heat and pressure could additionallyincorporate mechanical fastening elements such as staples. Such ainstrument is shown in FIGS. 6 and 6A, where a circular staplinginstrument 42 comprises a main shaft 43, a handle 44, a staple housing45, and an anvil 46. Anvil 46 is fixedly attached to the distal end ofanvil shaft 47, which is movably slidable within staple housing 45, mainshaft 43, and handle 44.

[0091] The distal surface 48 of staple housing 45 has slots 49 forstaples (not shown) and an electrically resistant coating or member 50.An inner circular member 51 with a cutting edge 52 is arrangedcircumferentially around anvil shaft 47, as can be seen more clearly inFIG. 6A. Optionally, slots 49 and coating 50 could be coextensive so asto facilitate direct heating of the staples.

[0092] Handle 44 comprises means for operating anvil 46 and heatingelement 49 and for firing the staples. As would be appreciated by thoseskilled in the art, a staple firing lever or member 53 can beoperatively connected to a cylindrical pushing member within staplinghousing 45 that causes the staples to be ejected from slots 49.

[0093] The operation of the circular stapling instrument would besimilar to that of instrument shown in FIG. 3, with the exception thatstaples would be fired into tissue to be joined. Preferably the stapleswould be fired subsequent to sealing and concurrently with the cutting.The staples would act in conjunction with the thermal energy to enhancethe strength of the tissue seal, joint or bond while the thermal energywould enhance the hemostatic capability of the staples. Staples or othermechanical tissue fasteners could be used in conjunction with thermalenergy sealing in configurations other than circular, such as linear orangled.

[0094]FIG. 7 depicts an embodiment of the invention that is essentiallya tissue-core removal instrument. The tissue core removal instrument 56comprises a cylindrical member 58 having a fixedly attached proximallyextending handle 60. Cylindrical member 58 comprises a sharp cuttingedge 62 and a heating element 64 arranged on the outer surface 66 ofcylindrical member 58. Optionally, sharp cutting edge 62 could bereplaced by a heating element to do the cutting.

[0095] Consistent with the description above, a tissue sample isobtained by inserting removal instrument 56 into an organ, withinstrument 56 being rotated as it moves forward. The rotation could beeither clockwise or counterclockwise, but preferably alternatinglyclockwise and counterclockwise, with sufficient pressure to cause edge62 to cut. Heating element will cauterize or seal tissue adjacent to thetissue 64 sample to be removed, and when a tissue sample of sufficientdepth is positioned within cylinder 58, instrument 56 will be removed.As is conventionally done, removal instrument 56 would preferablycontain means for removing a tissue sample, such as an internal piston59 having a proximally-extending actuator 60 to force the sample to beejected from the distal end of removal instrument 56. As would beappreciated by those skilled in the art, a tissue-core removalinstrument may optionally have additional cutting means at its distalend to assist in separation of a core tissue sample from the tissuemass.

[0096] In FIG. 8 the distal portion 70 of an electrothermal biopsyneedle comprises an outer cutting sheath 72 slidably circumferentiallyarranged around an inner slotted stylus 74 having a slot 76 to capture atissue sample 78. The outer sheath 72 has a cutting edge 73 whichseparates tissue sample 78 from the rest of the tissue mass (not shown)and encloses sample 78 in slot 76 when outer sheath 72 is propelleddistally by an actuator (not shown).

[0097] Outer sheath 72 preferably has an electrically resistant film 75coating on its distal portion. Film 75 may have spaced-apart electricalcontacts or connectors 77. In another embodiment of a biopsy needlewhere stylus 74 has an inner cutting member (not shown), the stylus orthe inner cutting member, or both, may have an electrically resistantcoating or film.

[0098] The aforementioned aspect of the invention could be incorporatedinto known biopsy instruments. See, for example, U.S. Pat. Nos.4,600,014 and 5,595,185, both of which are incorporated herein byreference with regard to their descriptions of biopsy instruments.

[0099]FIGS. 9 and 10 depict a circular cutting embodiment of theinvention in which a disk 80 having a sharp outer edge 82 is attached atits center to a rod 84 which is rotatingly secured to forks 86 of handle88. Adjacent edge 82 is a circular heating element 90, which can be onone or both surfaces of disk 80. Each heating element 90 is electricallyconnected to fork 86, for example, through one or more brushes 91.Optionally, sharp cutting edge 82 could be replaced by a circumferentialheating element to do the cutting.

[0100]FIG. 11 represents an embodiment of the invention where a heatingand cauterizing instrument 92 comprises a catheter 94 and an inflatableballoon 96 sealingly attached to the distal end of catheter 94. Catheter94 comprises at least one lumen 98, which is in fluid communication withballoon 96 for inflation and deflation. The proximal end of catheter 94is in fluid communication with a regulated pressure source or inflationsource (not shown) for inflating and deflating balloon 96.

[0101] Balloon 96 has an electrically resistant film coating 100, atleast two separate portions of which are connected to wires 102 thatextend proximally along or within catheter 94 to a power source 104. Theelectrically resistant film coating 100 is intended to cover asubstantial portion, if not all, of the outer surface of balloon 96.

[0102] In use, instrument 92 with a deflated balloon 96 is manipulatedwithin a patient's body, e.g., intracorporeally or even percutaneously,to position balloon 96 adjacent to a site to be cauterized. Then,balloon 96 is inflated so that the electrically resistant film coating100 contacts the area to be cauterized, whereupon film coating 100 isenergized with electrical energy from source 104. After the heat andpressure produce the desired effect, the power is turned off and theballoon is deflated to facilitate removal.

[0103] With regard to the embodiments of the invention depicted in FIGS.3 to 11, it should be appreciated that the respective heating elementsare electrically connected to an appropriate power supply. It isenvisioned that in each instance the power supply can be a battery orbattery pack, which can be fixedly attached or integral with to therespective instrument. Optionally, the battery or battery pack could beseparately mounted or positioned, such as on a clip or belt means forthe operator to wear. It is within the scope of the invention that otherstandard sources of electrical power, such as transformers, may also beused. Other sources of heat such as fuel, e.g., butane, or chemicalreactions, may be used.

[0104] As mentioned above, one aspect of the invention concernsoptimization of (1) thermal energy application, i.e., temperature andtime, and (2) pressure, i.e., force and duration, to achieve maximumtissue seal strength and minimal collateral tissue damage. Those skilledin the art will appreciate that useful parameters will vary greatly.

[0105] However, in practical application to human tissue a voltage offrom about 0.5 volt to about 14 volts, preferably from about 1 volt toabout 12 volts, will be applied to a heating element having a resistancesufficient to generate thermal energy to heat tissue to a temperatureadequate to cause denaturation of proteins. This temperature is in therange of about 45° C. to about 100° C. The pressure applied would besufficient to provide coaptation but less than would crush or destroythe tissue itself.

[0106] The strength of tissue coagulations, seals, anastomoses or weldscan be experimentally measured. For example, the strength of acoagulation produced on the side of a lacerated blood vessel can bemeasured experimentally by first producing the coagulation and thenapplying measured amounts of hydrostatic pressure to the inside of thevessel until the coagulation blows off and bleeding recommences. Thestrength of a tissue weld can be measured by first joining two pieces oftissue together and then placing the joined tissues in a machine whichattempts to pull the tissue apart with increasing and measured amountsof force. Collateral thermal damage is also a measurable quantity inthat the amount of collateral thermal damage can be readily assessedvisually or microscopically. By use of this methodology, a table ofoptimized parameters could be constructed for any type of tissue. Theseparameters would be incorporated into the various instruments by meansof selecting the voltage, current, and resistance of the heatingelements and also the amount of pressure used to press the tissuetogether during the coagulating/sealing/joining process, as well as thetime duration of the process. These parameters can simply beincorporated into the instrument (i.e., simple mechanical timer, fixedpreset voltage and current, and spring-loaded pressure instruments, or,we can incorporate more flexible and active controls based onmicroprocessor regulation of the heating process, guided by a “look-up”table in ROM and by using sophisticated mechanical force/pressuresensors and strain gauges) . Also, for certain applications, it may besufficient to have a skilled operator, visually or by other sensingmeans, determine the duration of energy application and the amount ofpressure required.

[0107] The instruments of the present invention may be constructed ofany suitable material, such as will be familiar to one skilled in theart, for example, out of a reinforced engineered plastic such asfiberglass reinforced polycarbonate, or machinable or injection-moldedceramics, or high temperature glass or epoxies, or mica. Alternativelythey may be constructed out of a suitable alloy steel such as 318stainless steel, or the like. The heating element may be a simpleresistive wire or may be a thin film or coating composed of metallic,organo-metallic, or organic materials which may be conducting orsemi-conducting. The actual materials of construction will be a matterof choice depending upon whether the instrument is to be employedrepetitively or in a disposable manner. Indeed, in the latter situationit is contemplated that different parts of the instrument may beconstructed of metal alloy and/or plastic, in which situation theplastic disposable components can be thrown out after each use and themore expensive metal alloy components reused. If sophisticated andexpensive control circuitry is used, this part of the instrument couldbe made in a reusable manner.

[0108]FIG. 12 illustrates an embodiment of a forceps instrument 210which may be variously described as a pincer or tweezers. Forcepsinstrument 210 comprises forceps arms 212 and 214, the proximal ends 216and 218, respectively, of which are attached to switch housing 220. Theouter surfaces of forceps arms 212 and 214 contain finger grips 222 toassist the operator in holding and activating forceps instrument 210. Anoptional sleeve 221 covers the proximal portion of housing 220.

[0109] Forceps arms 212 and 214 may be formed of a suitable resilientmaterial such as stainless steel, for example, that has the desiredcombination of stiffness and spring rate. For disposable applicationsforceps arms 212 and 214 may be formed from a homogeneous plasticmaterial, or a material that is filled with particulate material toincrease stiffness or abrasion resistance.

[0110] Alternatively, forceps arms 212 and 214 may be formed from acomposite material tailored to provide the desired stiffness accordingto specific functional and ergonomic needs and to provide heatresistance for electro-surgical and thermosurgical applications. Thecomposite material may be any composite construction, e.g., fibermaterial, glass, carbon fiber, Kevlar, aramid, or metallic particlesbound with an epoxy, polyester, or other resin, forming the compositematrix.

[0111] Forceps arms 212 and 214 may be manufactured in a unitaryconstruction, via casting, lay-up, compression molding, lamination, ormolding of a pre-impregnated fiber cloth in a manner known to oneskilled in the art. The forceps arms may also be molded or cut frompre-formed sheet composite material and glued or riveted together.Components may also be filament wound. Alternatively the components maybe stainless steel with a flex circuit.

[0112] The composite matrix may also have molded into it conductivewires or strips for transmission of electrical energy or transmission ofdata signals. The carbon in the carbon fiber matrix may also be used toconduct electrical or data signals. The fiber in the matrix, which maybe carbon, glass, Kevlar, aramid, or other fiber, may be laminated suchthat the unidirectional fibers are oriented at an angle to one anotherto achieve the desired spring rate and stiffness characteristics.

[0113] One or both of the distal ends 224 and 226 of forceps arms 212and 214, respectively, contain a heater wire 228, as shown in greaterdetail in FIGS. 15 and 16. Each of said distal tips 224 and 226comprises a non-slip sleeve or “bootie”, such as heater sleeve 230 ondistal tip 224 and anvil sleeve 231 on distal tip 226, which sleeves maybe comprised of clear or opaque, deformable, resilient, non stickmaterial. Suitable materials include polytetrafluoro-ethylene (PTFE),available as TEFLON®, graphite, KAPTON, mica, or silicone. Each sleeve230,231 evens out pressure against tissue and insulates the surfaces offorceps arms 212 and 214 electrically and thermally. Sleeves 230,231 mayalso incorporate thermally reflective material as layers or coatings.Useful reflecting materials would include ceramics, thermally reflectivemetals, or thermally reflective polymers, such as MYLAR®polymericcompositions. Sleeves 230,231 also prevent heat dissipation and focusheat from heater wire 228 on a specific area, while spreading the heatsufficiently to obtain a good seal zone. By insulating and reflecting,i.e., managing, the heat generated by heater wire 228, sleeves 230,231minimize power consumption to achieve the intended result. Also, theresiliency of sleeves 230,231 is intended to lengthen the useful life ofheater wire 228, which becomes fragile when hot.

[0114] Switch housing 220 comprises a finger-operated switch 232, e.g.,a multi-directional post-in-tube design, preferably a high current, lowvoltage switch. When a button 234 is pushed into the plane of forcepsarms 212 and 214, from either direction, switch 232 is activated so thatcurrent is provided to heater wire 228. When button 234 is released, thebutton returns to its starting position and the flow of current isinterrupted. Optionally, housing 220 comprises at least one anti-swivelguide 235 to form a channel to help maintain forceps arms 212 and 214parallel to one another. In addition, the forceps may be used with afoot-activated switch instead of a finger-activated switch. The sameswitch housing may be used, but without a finger switch. Instead, thecircuit may be completed by depressing a foot switch that is connectedvia an electrical cable between the battery pack and the forceps powercord.

[0115] In a preferred embodiment of the invention switch housing 220comprises circuitry to control or manage the current supply to heaterwire 228. This circuitry, known generally as an “actuator” is animportant and useful feature. Deterioration of heater wire 228 isprevented by contact of heater wire 228 with the heat sink of thepinched tissue and the opposing forceps arms. The presence of theactuator induces the operator to apply a minimum amount of pressure tothe closed forceps distal tips, which insures good sealing/welding ofthe vessel or organ tissues. In addition there is the important safetyaspect that the actuator prevents inadvertent exposure of heating wiresto drapes or other flammable materials in the operating room, should thefinger-operated switch be inadvertently activated.

[0116] As can be seen more clearly seen in FIG. 15, at least one distaltip of one of the forceps arms, such as distal tip 224 of forceps arm212, comprises heater wire 228 on the outer surface of heater sleeve230, preferably with a slight gap between distal tip 224 and heatersleeve 230, which gap could be filled with a fluid such as a gas orliquid. This provides for additional thermal insulation between heaterwire 228 and forceps distal tip 224. Heater wire 228 may comprise anyuseful electrically resistant, preferably nonstick material such asnichrome or an alloy thereof, graphite, nitinol, stainless steel,platinum, or tungsten, uncoated or coated with a non-stick material suchas graphite. In fact, any material may be used such that the heater wire228 has a lower Ohmic resistance than body tissue. This lower resistanceallows the resistive element to be exposed but not transfer electricitythrough the tissue. The length, diameter and material selection areadjusted to optimize sealing and cutting. Although heater wire 228preferably has a round smooth surface, wire 228 may be other then roundand have a textured surface to increase traction. A flat surface wouldbe better for sealing applications, whereas a pointed surface would bebetter for cutting applications. It is within the scope of the inventionthat heater wire 228 may be a flex circuit or just a very flat wire.While heater wire 228 is shown in FIG. 12 as being substantiallystraight, heater wire 228 could instead be curved or arcuate.

[0117] Heater wire 228 is connected by solder to broader, flat wire 236,which is in turn soldered to the distal portion 238 of a copper striplaminated to the inside surface 240 of forceps arm 212. Flat wire 236 iscovered by a polymeric sleeve 242.

[0118] Distal tip 226 of forceps arm 214 comprises sleeve 230 having athicker inner surface 244, which inner surface 244 may comprise anintegral part of sleeve 230 or a separate component that has beenadhered to the inner surface of sleeve 230. In a preferred embodiment ofthe invention, said inner surface comprises a separate polymeric memberthat has been glued or fused with sleeve 230, optionally with moldedridges on the surface facing heating wire 228 to improve grip/tissuetraction.

[0119] Heater wire 228 is electrically connected through cord 249 to apower source such as a battery pack 250. Battery pack 250 can compriseany number of commonly available batteries (such as D cells or AAcells), dependent upon application. Battery pack 250 may optionallycomprise sensing circuitry and a vibrating or auditory alarm to indicatea “low battery” situation, to minimize sticking and peeling of tissuewhen the battery is low and heater wire 228 would not be hot enough toseal or cut. Preferably, there will be a tone from housing 230 orbattery pack 250 to indicate the forceps has been activated, withanother tone or vibration to indicate that the battery is low. Whilethere could be a cutoff rather than a low battery signal, it is believedthat a low battery signal is preferable. It is intended that the batterypack will be capable of being clipped to the operator's uniform orsuspended on an IV pole, or otherwise positioned in a convenientlocation adjacent the treatment area. Preferably the battery pack isconnected to instrument 210 with a releasable connection 252 so thatbattery pack 250 can be readily replaced. The proximal portion of sleeve221 may comprise a swivel connection 253 with cord 249.

[0120] The preferred power source is a steady DC battery pack. It iswithin the scope of the invention that the power source could be a walloutlet plug-in transformer of steady DC, pulsed DC, low frequency AC, oreven RF. One could also provide for a cutoff ability, for example, inthe event of a short circuit or wire break, and/or a temperaturefeedback, optionally with a control to minimize temperature for sealingand maximizing temperature for cutting. Also, optionally there would bea feedback to power capability to automatically adjust for use underliquid conditions, e.g., saline, versus non-liquid conditions, to reducethe risk of wire burnout.

[0121] In the event that the power supply has DC/RF capability, theforceps can also function as an RF instrument. If the distal tips of theforceps arms were closed and then tissue was contacted, the RF/forcepswould act like a hemostatic electrode or blade. Optionally a sleevecould be removed and replaced with a Bovie blade. (Also, the instrumentcould be activated with a dedicated hand switch or a foot switch.)

[0122] A primary application of the forceps instrument shown in FIGS. 12to 16 is to seal and cut tissue such as blood vessels, other corporealvessels or ducts, corporeal organs, and vascularized tissue. It is alsouseful for sealing in the lymphatic system. The way in which saidforceps works can perhaps be appreciated by referring to FIG. 17, whichcomprises a representative graph of the temperature gradient in a vesselor tissue (“tissue”) to which this instrument is applied. At the portionof tissue in direct contact with or immediately adjacent to a heaterwire, the temperature of the tissue will be very hot—sufficiently hot tosever the tissue. At the same time, at the areas of tissue immediatelyadjacent to and roughly parallel to the “cut zone”, the tissue will beheated but not to the same extent as in the cut zone. In these twosecondary areas, each referred to as a “seal zone,” tissue will becauterized and sealed. This tip configuration allows for expedientdivision and sealing of blood vessels or vascularized tissue with thesimple process of closing the forceps arms and momentarily applying heatenergy at the forceps tips. This process will divide and seal thetissue. Additionally, when the tissue is gripped under moderatetraction, the tissue will often automatically fall away from the jaws ofthe forceps as the heating element divides and seals the tissue. Heatfrom the heating element conducts laterally into the adjacent tissuewhile it is being compressed within the forceps tips. As a result, thistissue is often completely sealed by the time it is divided and fallsaway from the forceps jaws. This way, the divided tissue will not bleedas it is divided. The surgeon moves to a new area of tissue to bedivided hemo-statically, and this simple process is repeated. With thisapproach to cutting and coagulation, significant time and materials canbe saved, reducing the need for applying clips or ligatures, or for theuse of other hemostasis products or techniques. Thus, with thisparticular embodiment of the invention, tissue can be cut and cauterizedwith one fairly simple repetitive motion.

[0123] The time vs. temperature graph shown in FIG. 18 illustrates theprinciples involved behind the process of sealing and cutting with theforceps device. After tissue is grasped between the forceps tip, theheat is activated by the button 234 at t=O. As the heating element heatsup, heat is conducted into the tissue being grasped. As the temperatureincreases with time, the tissue passes the temperature value necessaryfor sealing and hemostasis (and eventually approaches the temperaturenecessary for dividing the tissue). Tissue closer to the heater ishotter than tissue farther away from the heater. Eventually (typicallyat t=2 to 5 seconds) the tissue immediately adjacent to the heaterbecomes hot enough that it divides. This division usually occurs afterthe tissue slightly farther away from the heater has reached asufficiently elevated temperature for sealing and/or coagulation tooccur there. Alternatively a pre-programmed “lock out” interrupts thepower supply, so that the tissue remains at the appropriate temperaturefor the appropriate time, for example, 100° C. for approximately onesecond, whereupon the tissue is severed and then cools.

[0124] In the embodiment of the invention set forth in FIGS. 19 and 20,a clamp 302 comprises a cartridge 304 that can be removably attached toclamp 302. Clamp 302 is essentially a common surgical clamp that hasbeen adapted to receive cartridge 304. Cartridge 304 comprises anelongated member 306 having a switch housing 308 with a switch activator310. The distal end of member 306 comprises a heating element 312 thatis in electrical connection with switch housing 308 and a power supply(not shown).

[0125] The embodiment of the invention shown in FIG. 21 is amodification of the embodiment shown in FIGS. 12 to 16 intended forlaparoscopic application. According to this embodiment an elongatedmember 320 is attached at its proximal end 322 to a handle 324 housingcomprising hand grips 326 and 328 attached to grip members 330 and 332,respectively. The distal end 334 of elongated member 320 comprisesgripping arms 336 and 338, at least one of which has a heating element340. Gripping arms 336 and 338 may optionally have sleeves (not shown).

[0126] An actuator rod 342 has a proximal end 344 rotatively attached togrip member 330 at fastening point 346, and the distal end 348 ofactuator rod 342 is operatively connected to gripping arms 336 and 338.Grips 326 and 328 and their respective grip members 330 and 332 aremovably connected at pivot point 350, so that when grip 326 and 328 aresqueezed together, proximal end 344 moves proximally and gripping arms336 and 338 move together. A rotating positioner 352 can rotate to inturn rotate elongated member 320 and gripping arms 336 and 338.

[0127] Grip member 332 preferably contains a finger-activated switch 352to control the flow of electricity to heater wire 340.

[0128] In FIG. 22 one embodiment of the operative connection betweenactuator rod 342 and gripping arms 336 and 338 is shown. Distal end 348of actuator rod 342 is movably connected to a link 360 which is movablyconnected to member 362. Gripping arms 336 and 338 rotate in oppositedirections about pivot point 364 to close or open upon tissue. Whenactuator rod 342 moves in the proximal direction, gripping arms 336 and338 close together. Upper gripping arm 338 comprises heater wire 340,such as a nichrome wire, which is thermally and electrically insulatedfrom gripping arm 338 by insulator 366. Here, the distal portion 370 ofheater wire 340 is spot welded to the exterior surface 372 of grippingarm 338. The interior surface 374 of gripping arm 336 is preferablyinsulated, for example, with a silicone polymeric insulator. Heater wire340 is operatively connected through wire 376 to a power source (notshown) and/or switch 352.

[0129] A detail of FIG. 22 is shown in FIG. 23, where the relationshipbetween gripping arms 336 and 338 can be better appreciated, especiallyfor he curved embodiment shown.

[0130] Member 362 and lower gripping arm 336 are integral andcooperatively arranged with upper gripping arm 338 and member 380 aroundpivot 364. The interior surfaces 382 and 374 of gripping arms 338 and336, respectively each having polymeric insulation inserts.

[0131] As has been shown, the materials and the principles described forthe tip design of the forceps can be modified slightly and applied tothe clamp and to the laparoscopic grasper. Just as the design can beadjusted to a clamp and to a laparoscopic grasper, it can be applied tovirtually any hand-held surgical instrument.

[0132] A monopolar RF version of a hook dissector is used inlaparoscopic surgery. The embodiments of the invention shown in FIGS. 24and 25 comprise a surgical dissecting instrument in the form of a hook,and this hook offers safety advantages over the RF version since theheating effect is confined to the tissue caught up in the hook. Theheating element, preferably a nichrome wire, is situated on the innersurface of the hook so that tissue is compressed against the heater wirewhen tissue is “hooked” with the instrument.

[0133] The instrument shown in FIG. 24 comprises an elongated member 402having a proximal end 404, optionally textured to facilitate gripping,and a distal, hooked end 406. The interior surface 408 of hooked end 406comprises a heater wire 410, which is operatively connected through wire412 to a power source (not shown). The distal end 414 of heater wire 410can be spot welded to hooked end 406, which provides a return path forelectricity to the heater wire. Isolative material 416 between heaterwire 410 and hooked end 406 thermally and electrically insulates heaterwire 410. Optionally, insulation material 416 comprises a polymericmaterial in the form of a sleeve.

[0134] Elongated member 402 preferably comprises a physiologicallyacceptable, sterilizable metal such as stainless steel. Non-conductiverigid materials can be used so long as a pathway for electricity fromthe distal end heater wire 410 is provided.

[0135] In FIG. 25 an elongated member 430 has a proximal end 432,optionally textured, and a distal, hooked end 434. The lateral interiorsurface 436 of hooked end 434 comprises a heater wire 438. Heater wire438 extends from a spot weld 446 into distal end 434 to a looping point440 and then proximally. Through spot weld 446 heater wire 438 is inelectrical connection with elongated member 430. Elongated member 430 isconnected to one pole of a power source (not shown). The other end ofheater wire 438 extending in the proximal direction after looping point440 extends to wire 442 through an electrically and/or thermallyshielded pathway 444. Wire 442 is connected to the other pole of thepower source.

[0136] Elongated member 430 comprises a rigid, or substantially rigid,physiologically acceptable, sterilizable material. Useful materialsinclude stainless steel and other conducting metals or alloys. It iswithin the scope of the invention that the distal portion of elongatedmember 430 could be comprised of a rigid or substantially rigidnon-conducting material such as a suitable polymer, for example,polystyrene or an ABS polymer or copolymer

[0137] It is intended that all matter contained in the above descriptionand shown in the accompanying drawings shall be interpreted asillustrative and not in a limiting sense. Also, it is understood thatthe following claims are intended to cover all of the generic andspecific features of the invention herein described and all statementsof the scope of the invention which, as a matter of language, might besaid to fall therebetween.

We claim:
 1. A body tissue cutting device comprising: a handle sectionand a first and second grasping arms extending from the handle section,said first and second grasping arms being resiliently mounted to thehandle to allow closure of the grasping arms by hand, said first andsecond grasping arms each having a distal end with a grasping face, saidgrasping face on each grasping arm aligned to meet the grasping face ofthe other grasping arm upon closure of the grasping arms; a wiredisposed upon the grasping face of the first grasping arm so that itlies between the grasping face of the first grasping arm and thegrasping face of the second grasping arm upon closure of the graspingarms, said wire being operably connected to a source of electricalpower; said wire being secured to the distal end of the first graspingarm and extending proximally over the grasping face of the firstgrasping arm toward the proximal end of the first grasping arm.
 2. Thedevice of claim 1 further comprising: a resilient surface on thegrasping face of the first grasping arm, between the wire and thegrasping face of the arm.
 3. The device of claim 1 further comprising: asleeve covering the distal end of the first grasping arm, therebyforming a surface on the grasping face of the second grasping arm, saidsleeve being separated from the distal end of the first grasping arm bya small fluid-filled gap.
 4. The device of claim 1 further comprising: aresilient sleeve covering the distal end of the second grasping arm,thereby forming a resilient surface on the grasping face of the secondgrasping arm.
 5. The device of claim 1 further comprising: a resilientsurface on the grasping face of each of the first and second graspingarms.
 6. The device of claim 1 further comprising: a sleeve covering thedistal end of the first grasping arm, thereby forming a surface on thegrasping face of the first grasping arm, between the wire and thegrasping face of the arm, said sleeve being distanced from the distalend by a small fluid-filled gap. a resilient sleeve covering the distalend of the second grasping arm, thereby forming a resilient surface onthe grasping face of the second grasping arm.
 7. The device of claim 1wherein the grasping arms comprise a pair of tweezers.
 8. The device ofclaim 1 wherein the grasping arms comprise a forceps.
 9. A medicaldevice comprising: a pair of tweezers characterized by a first arm and asecond arm, each of said arm having a proximal end and distal end, saidfirst arm having a first gripping face disposes on the distal endthereof, said second arm having second gripping face disposes on thedistal end thereof, said gripping faces being defining surfacesgenerally perpendicular to a plane defined by the grasping arms, saidsurfaces being movable into apposition with each other upon closing ofthe tweezers; a first layer of resilient material disposed on thegripping face of the first arm; a second layer of resilient materialdisposed on the gripping face of the second arm; a wire disposed betweenof the first and second layers of resilient material so as to be trappedbetween the gripping faces of the first and second arm upon closing ofthe tweezers.
 10. A medical device comprising: a pair of forcepscharacterized by a first arm and a second arm, each of said arm having aproximal end and distal end, each of said arm being rotatably fixed tothe other at a midpoint thereof, said first arm having a first grippingface disposes on the distal end thereof, said second arm having secondgripping face disposes on the distal end thereof, said gripping facesbeing defining surfaces generally perpendicular to a plane defined bythe grasping arms, said surfaces being movable into apposition with eachother upon closing of the forceps; a first layer of resilient materialdisposed on the gripping face of the first arm; a second layer ofresilient material disposed on the gripping face of the second arm; awire disposed between of the first and second layers of resilientmaterial so as to be trapped between the gripping faces of the first andsecond arm upon closing of the forceps.
 11. A medical device comprising:a laparoscopic grasper characterized by a first arm and a second arm,each of said arm having a proximal end and distal end, each of said armbeing rotatably relative to the other about a point near the distal endthereof, said arms being adapted to be inserted into the body and to berotatably opened and closed upon each other within the body, said firstarm having a first gripping face disposed on the distal end thereof,said second arm having second gripping face disposes on the distal endthereof, said gripping faces being defining surfaces generallyperpendicular to a plane defined by the grasping arms, said surfacesbeing movable into apposition with each other upon closing of thegraspers; a first layer of resilient material disposed on the grippingface of the first arm; a second layer of resilient material disposed onthe gripping face of the second arm; a wire disposed between of thefirst and second layers of resilient material so as to be trappedbetween the gripping faces of the first and second arm upon closing ofthe graspers.